1. Field of the Invention
The present invention relates to a power tool and has particular although not exclusive, relevance to battery powered tools.
2. Description of the Related Art
It is conventional for power tools to be designed and built for a dedicated purpose, such as a drill, a jigsaw or a sander. If the user needs to undertake a sanding operation he will use a dedicated sander. If then he needs to drill a hole in a workpiece he will swap the sander for a dedicated drill, and so on.
Whilst such swapping over of dedicated tools is not inconvenient, it does mean that, particularly for the person who needs to use power tools relatively infrequently, considerable expense is incurred in acquiring a broad range of these dedicated power tools.
Furthermore, in the case of so-called "cordless" or battery-powered tools, the user will either need to change the battery pack when changing dedicated tools, or have several ready-charged batteries available for use. These alternative options are cumbersome or expensive respectively.
Solutions to the above problems have been proposed in the past and one such solution entails providing a power tool including a motorised drive which is capable of accepting any one of a plurality of discrete attachments which achieve a dedicated purpose. This means that rather than purchasing a dedicated entire power tool for each job, the user only has to purchase a dedicated attachment (which is cheaper than a dedicated entire tool) and just swap these over as and when necessary.
There still exist certain problems with such solutions, however. In a system such as the discreet attachments described above, it is important to achieve a high degree of alignment between the body of the tool providing the drive and the attachment which receives the drive. In the case of a rotational drive such as a drive shaft, a high degree of axial alignment between the driving and driven shafts is imperative in order to achieve an efficient transfer of energy between the two and also to avoid creating unnecessary mechanical wearing at the interface between the shafts.